Trains in parts of southern England have been severely disrupted after a fault in a radio system.

Services out of London Waterloo, one of the UK’s busiest rail stations, have been particularly delayed.

A problem with the radio network preventing communication between drivers and signallers was reported towards the end of the morning rush hour, affecting the railway’s Wessex route connecting London with the south and south-west.

The fault has now been fixed, but disruption is expected to continue in places until the end of the day. A number of services have been cancelled, or delayed by up to an hour and a half.

Train companies advised passengers to expect some disruption, allow more time for journeys and check before travelling through the day.

The most-affected operator is South Western Railway (SWR), with trains struggling to return to normal. Some routes run by Southern were also curbed or delayed, while a number of CrossCountry, Gatwick Express, Great Western Railway, London Overground and Thameslink trains were disrupted.

The National Rail website reported that the technical problem had been resolved by 11am but warned: “Some services may still be delayed by up to 90 minutes or cancelled whilst service recovers. Major disruption is expected until the end of the day.”

SWR said services across its entire network “may be cancelled, delayed by up to 90 minutes or revised” for the rest of the day, reporting major disruption on its routes as far west as Exeter.

Southern said that trains on its Hayward Heath route would be running late or ending at Gatwick until at least 1pm.

Passengers have been told that they can use their tickets on alternative routes or operators at no additional cost.

A Network Rail spokesperson said: “Due to issues with radio communications, train services in the south-west and south have been subject to some delays this morning.

“Staff have worked to resolve the fault and train services are now returning to normal. We apologise to passengers for the disruption caused to their journeys this morning.”

Heathrow’s new chair has opened talks with airlines and the billionaire local landowner Surinder Arora to defuse a row that threatens to further delay the £49bn plan to build a third runway at Europe’s busiest airport.

Philip Jansen, who was appointed at the start of the year, is understood to have held meetings with the airport’s carriers and with Arora, who has been promoting his own £25bn expansion scheme, in the hope of finding the middle ground in a row over cost and service issues.

Last week the former BT boss and Thomas Woldbye, the chief executive of Heathrow, met International Airlines Group, the parent company of British Airways.

British Airways dominates Heathrow, accounting for more than 50% of slots, and the IAG chief executive, Luis Gallego, has said the cost of the third runway and associated works must be capped at £30bn.

Jansen is also understood to have held talks with Virgin Atlantic and Arora, a multibillionaire hotelier who has for years criticised the airport for “ripping off” passengers, airlines and retailers with high charges.

BA, Virgin and Arora are all part of Heathrow Reimagined, a campaign group seeking to drastically reduce the costs of operating at the airport. The airlines, as well as large carriers from the US, have refused to back the expansion plan “at any cost”.

Heathrow is considered to be Europe’s most expensive airport, and in March the UK aviation regulator rejected its plans to significantly raise its landing fees to fund a multibillion-pound upgrade.

“All airlines and their stakeholders agree over the necessity and long-term economic value of a third runway,” a source familiar with the talks said. “There are just differing points of view. Airlines want the lowest possible cost, other people want to get involved and think it can be done cheaper. Whatever happens, we are all going to have to work together. There needs to be good relations if we want to re-engineer a way forward.”

The chancellor, Rachel Reeves, has thrown the government’s weight behind the expansion, pledging that work will begin before the next election, after decades of controversy and opposition over costs and the local and environmental impact.

In November, ministers backed a plan for the runway to be up and running by 2035, before the rival proposal submitted by Arora Group, although Heathrow is still seeking formal planning approval to start construction by 2029.

Heathrow is owned by a consortium of investors led by the French company Ardian and includes the sovereign wealth funds of Qatar, Singapore and Saudi Arabia.

China Investment Corporation, which owns 10% of Heathrow, is reportedly considering selling its stake over concerns about rising costs as the expansion project rolls out, according to the Financial Times.

A spokesperson for Heathrow said: “As newly appointed Heathrow chairman, Philip Jansen is spending time meeting with the airport’s key stakeholders. Building constructive relationships with them and especially our airline and commercial partners is essential to deliver our shared goals of excellent customer experience and fulfil our vision of being an extraordinary airport, fit for the future.”

Jansen has built something of a reputation for bringing together opposing parties to tackle difficult corporate stalemates.

At BT he engineered the signoff of £15bn in funding to roll out full fibre broadband across the UK, after decades of wrangling between stakeholders, making a promise to “build like fury” and address the national embarrassment of the UK’s status as a global laggard in internet connectivity.

The beleaguered London-listed WPP drafted in Jansen as the chair at the beginning of last year, promptly resulting in the removal of the chief executive, Mark Read, as the advertising company restructures under the former Microsoft boss Cindy Rose.

Separately, Aviation Services UK, which represents ground-handling companies such as Menzies, Swissport and Dnata, wrote to the aviation minister, Keir Mather, warning that the sector may need a Covid furlough-style scheme for employees if there are widespread flight cancellations because of fuel shortages this summer.

The ground-handling sector, which manages baggage and check-in services at airports and employs about 30,000 people, is remunerated on the basis of planes flying routes.

The issue of cutting and rehiring staff, who require lengthy security vetting to work in airports, became apparent during the Covid pandemic, when shortages caused chaos as airports began to get back on their feet.

It is afternoon rush hour on the M4 and drivers are yet again making slow progress around the city of Newport, often seen as the gateway to south Wales given its location between Cardiff and Bristol.

Cars and lorries are stuck in gridlocked traffic in both directions on the approach to the Brynglas tunnels, where the road narrows to two lanes in each direction, while flashing lights warn motorists in Welsh and English of a ciw (queue).

Traffic jams may be an everyday reality for commuters and businesses trying to move goods around, but they have also become a hotly debated topic before the Senedd elections on 7 May, in a vote predicted to bring sweeping political change to the principality, and send Labour into opposition for the first time since devolution in 1999.

Congestion on this part of the M4 – the main route linking south Wales with England – has been complained about by businesses and commuters for decades, while a relief road around Newport has been proposed for almost as long. Motorists say tailbacks cost time and money, and make the country less attractive to potential investors.

Poor public services, and frustration over long waiting times for NHS treatment, rank top of the concerns for Welsh voters before the election, along with disappointment with transport services and infrastructure like roads, rail and buses.

“If there is an accident on the motorway, the whole of Newport is gridlocked,” says Rosemary, 81, waiting at the city’s bus station. “We could have done with that new relief road, it would have been a big help.”

The retired shop worker is dependent on buses to visit the shops and her daughter in a nearby town. “It’s not a very reliable bus service, it’s become really poor since the pandemic,” she says.

The six main political parties are split over how to tackle the tailbacks, and the issue prompted fiery exchanges during a leaders’ debate.

Two people in the running to become the next first minister, the leader of Plaid Cymru, Rhun ap Iorwerth, and Reform UK Wales leader, Dan Thomas, both support a new road, along with the Conservatives. Meanwhile, Labour, the Greens and the Liberal Democrats have declared themselves against.

After years of political indecision, soaring costs and opposition from environmental groups, the relief road project was finally scrapped by the Labour-led Welsh government in 2019, citing the projected £1.4bn cost, and the adverse impact on its planned location on the Gwent Levels nature reserve.

Opposition parties have criticised Labour for the £114m spend on the project before cancellation, although the party has pledged to improve public transport, cap adult bus fares and expand the “South Wales metro” rail electrification project. The network of tram-trains, able to run on rail and tram lines, is over budget, but scheduled to enter service shortly.

On a bright spring day, the sun glints off the river Usk that flows through Newport before reaching the Severn estuary and spanned by the transporter bridge, symbolising the city’s industrial heritage when huge quantities of Welsh coal and steel were loaded on to ships at its docks.

“The No 1 issue for my members is the M4, the congestion and uncertainty,” says Josh Fenton, senior policy manager at industry body Logistics UK. “The longer HGVs are sat in traffic, that’s adding to cost, making things more difficult, and potentially putting some businesses off setting up locally.”

Any new road would cost considerably more than the £1.4bn previously estimated, after recent construction cost increases and inflation.

The cost could be “potentially even up to £2.5bn and the Welsh government’s capital budget is about £3bn,” says David Philips, head of devolved and local government finance at the Institute for Fiscal Studies (IFS).

“Even if they were to do this over two terms, you’re looking at some £300m a year, which is 10% of the Welsh government’s capital budget. Then there’s lots of ambition for other things, like social housing, railways and investment in school and health facilities,” adds Philips.

The two parties topping the polls, Plaid and Reform, agree on the need for a new road, yet hold differing views on how to pay. At the Newport launch of Reform’s manifesto for the Senedd elections, party leader Nigel Farage said he would build a “toll road”, while Plaid have not laid out how they would fund the scheme.

“It comes with some kind of cost,” says Philips. “Either you need to borrow in an expensive way, or you need to cut back some other areas, or you need to raise additional revenue.”

Putting 1p on all rates of income tax across Wales could raise £400m a year, Philips calculates, although he notes “you could say this is for an investment in transport, but people in north Wales wouldn’t be very happy about that”.

Plaid and Reform also offer vastly differing visions for the Welsh economy: Reform has previously proposed reviving Wales’ industrial past, including coal mining and steel making, while Plaid has promised to increase public procurement from Welsh businesses and create a new national development agency.

Whoever runs the next government in Cardiff will face a “Welsh budget under significant pressure”, according to the IFS, amid a slowdown in increases in UK government funding, and a growing demand for health and social care, prompting the thinktank to call on the main parties to be “more upfront about fiscal reality”.

Back in the 1970s, when Wales began to lose mining and heavy industry, it had some success in attracting foreign investment, partly thanks to transport links offered by the M4. However, much of this investment proved temporary, and many large multinationals have come and gone in the intervening years, including carmaker Ford, which closed its Bridgend engine plant in 2020, as well as South Korea’s LG and white goods manufacturer, Hotpoint.

Transport infrastructure could now deter other overseas investors from setting up in Wales, according to Gareth Jenkins, executive chair of manufacturer FSG Tool and Die, located a quick – or sometimes slow – 20 miles up the road from Newport in Llantrisant, which is also home to the Royal Mint, producer of the UK’s coins.

FSG employs about 100 people, mostly specialist engineers who make the tools that allow Starbucks to produce reusable cups, McDonald’s to make plastic sauce pots, and Tesla to make battery cases for its electric vehicles, for customers as far afield as the US and Bolivia.

Roads are “generally a nightmare”, says Jenkins. “I can’t prove it’s affecting inward investment, but, if I was an investor, I’d be thinking: ‘Can I get a good building cheaply? Where can I get my people from? Can I move my stuff?’” says the plain-speaking Welshman, who previously advised the Welsh government on the manufacturing sector after the financial crisis.

Manufacturing still accounts for about a sixth of Wales’s economic output, the highest share in the UK relative to the economy’s size, according to industry body, MakeUK. The sector employs 138,000 people in Wales, vital for a country with lower employment and higher economic inactivity than any other UK nation or region apart from Northern Ireland.

“For manufacturing in Wales, there’s two routes out, one in the north, one in the south. It’s not acceptable to say ‘We’ve got what we’ve got and we’re not going to spend any more money on the M4.’ You’ve got to move goods around and it isn’t going to go from Cardiff airport and is very unlikely to go from Port Talbot docks.”

The Welsh government recently won a case over its £205m decade-long subsidy package for state-owned Cardiff airport, brought by its rival in Bristol. Companies such as FSG are calling for an expansion in the airport’s cargo operations beyond several weekly freight flights to China, launched in 2024.

Public services and transport are the main concerns for Cheryl Tucker, and former colleagues Lisa Owen and Karen Jones, enjoying a coffee and a catch-up at a cafe around the corner from FSG.

Top priority would be more hospitals and improved medical care, Tucker says, adding “but you need a good road network to get to hospital or other places”.

Despite these frustrations, their disenchantment with politics means Tucker and her friends are not planning to vote in the Senedd election.